"Police received a 911 call from a couple of people in another building that saw two people acting suspiciously on the rooftop," Philadelphia Police Commissioner Richard Ross said.

Philadelphia police responded with the Counterterrorism Unit and several federal agencies.

On the same rooftop where the man and woman were discovered, police found camera equipment and several items that initially appeared to be suspicious, like a smoke bomb and a liquid.

"Right now it appears this individual may be a blogger that likes to do things with photography that's a little bizarre. We haven't ruled out anything, you never do, but it just appears that this is what this individual does, we're not condoning it," Ross said.

Police don't believe the pair was doing anything terror related and released them after charging only 28-year-old Ivan Wong from Edison, New Jersey with Criminal Mischief and Defiant Tresspass.